\begin{table}[htbp]\centering
\caption{Robust IV Estimates of Log Registrations on Log Highway Gas Use \label{tab:GasUseiv}}
\begin{tabular}{l*{4}{c}}
\hline \hline \multicolumn{5}{l}{\textit{Panel A: IV Estimates and Robust 95\% Confidence Intervals}} \\&            &            &            &            \\
\multicolumn{5}{c}{Dep. Var.: Log Number of Vehicle Registrations} \\ &         (1)&         (2)&         (3)&         (4)\\
$\gamma$    &      -0.290&       -0.28&       -0.51&       -0.67\\
95\% Conf. Set&[-0.77, 0.10]&[-0.75, 0.10]&[-3.27, 0.11]&\makecell{(-$\infty$, $0.26]$; \nextline $[4.01$, $\infty$)}\\
\makecell[l]{Data Source \nextline Controls}&        None&  Documented&\makecell{Large \nextline Undocumented}&\makecell{Small \nextline Undocumented}\\
State Fixed Effects&           Y&           Y&           Y&           Y\\
Year Fixed Effects&           Y&           Y&           Y&           Y\\
\makecell[l]{State-Specific Linear \\ Time Trends}&           Y&           Y&           Y&           Y\\
Common Controls&           Y&           Y&           Y&           Y\\
Number of Obs.&       2,429&       2,429&       2,429&       2,429\\
\hline \hline \multicolumn{5}{l}{\textit{Panel B: Anderson-Robin Test Statistics and P-Values}} \\&            &            &            &            \\
 \multicolumn{5}{c}{\underline{$ H_{0}:\gamma=11$}} \\ AR Stat&   12.314***&   12.184***&     6.232**&      3.181*\\
p-value     &       0.000&       0.000&       0.013&       0.074\\
            &            &            &            &            \\
 \multicolumn{5}{c}{\underline{$ H_{0}:\gamma=9.7$}} \\ AR Stat&   12.330***&   12.197***&     6.299**&      3.234*\\
p-value     &       0.000&       0.000&       0.012&       0.072\\
            &            &            &            &            \\
\multicolumn{5}{c}{\underline{$ H_{0}:\gamma=$1}} \\ AR Stat&   11.066***&   10.909***&    8.426***&     5.495**\\
p-value     &       0.001&       0.001&       0.004&       0.019\\
            &            &            &            &            \\
\multicolumn{5}{c}{\underline{$ H_{0}:\gamma=$-4.8}} \\ AR Stat&   11.424***&   11.394***&     4.431**&       1.937\\
p-value     &       0.001&       0.001&       0.035&       0.164\\
            &            &            &            &            \\
\multicolumn{5}{c}{\underline{$ H_{0}:\gamma=$-6.1}} \\ AR Stat&   11.616***&   11.569***&     4.706**&       2.110\\
p-value     &       0.001&       0.001&       0.030&       0.146\\
\hline \hline \end{tabular} \vspace{0.2cm} \begin{tablenotes} \begin{spacing}{0} \begin{footnotesize} \item \textbf{Notes:} The top panel of this table presents IV estimates and 95\% confidence sets robust to weak instruments of the linear relationship between log highway gas use and log vehicle registrations.  The bottom panel presents Anderson-Rubin chi-squared statistics along with p-values for different null hypotheses pertaining to the parameter estimated in the top panel. The unit of observation is state-year. The four specifications pertaining to different levels of  (DSCs) and control specifications are documented in Table \cref{ssec:Spec}. Confidence sets are based on standard errors clustered by state. * p\textless 0.1, ** p\textless 0.05, *** p\textless 0.01 \end{footnotesize} \end{spacing} \end{tablenotes} \end{table}
